1. Field of the Invention
The invention relates to adjustable beds and other reclining or sitting articles of furniture in which a supporting member carries an articulated frame including two or more mutually adjustable parts, such as a back member, a seat member and optionally a foot member. More particularly, the frame is mounted in the support member by horizontal, transverse axles which provide pivot points for the mutually adjustable parts.
2. Description of the Related Art
There are a number of different kinds of beds and other reclining and sitting articles of furniture currently on the market and equipped with adjustment devices for setting different angles between the back member, the seat member and the foot member in order to provide the article with alternative user positions. The most common examples are adjustable chairs, where the back member and seat member can be set at an angle in relation to each other in order to provide a position of rest or a more active sitting position. Similar solutions have been developed for beds, offering the possibility of assuming a position which is more suitable for reading in bed, etc.
Such adjustable beds and chairs are employed not only for reasons of comfort, but are particularly important in nursing and illness situations, such as in hospital or in nursing institutions where the user has to stay for lengthy periods, e.g. in a bed, or in connection with therapeutic chairs for dentists, doctors, etc.
Examples of adjustable beds and other reclining or sitting furniture can be found in U.S. Pat. No. 4,751,754 and in Finnish Patent No. 89867, both of which disclose adjustable hospital beds, as well as in Danish Patents No. 125771 and No. 145563, both of which disclose examples of adjustable frames for installation in beds. To some extent these previously known constructions have a relatively complicated design. They offer the possibility of different angular adjustments for both the back member, seat member and foot member of the surface of a bed. In previously known designs, a change in the sitting angle will result in a relatively radical change in the angle between the seat surface and the back surface, since the surfaces are rotated about fixed axles. Due to the fact that the foot member is connected to the seat member and is slidingly guided in the frame of the bed, it will be raised above the surface of the bed in the knee area, which is not always desirable. Alternatively, special joint constructions or additional surface elements leave been employed.
Such an alternative is, for instance, described in U.S. Pat. No. 4,403,357. The reclining furniture of this patent includes a back member, a seat member and a foot member, and in addition, a flexible intermediate member between the seat member and the back member. The pivot axles of the seat and foot members are slidingly guided in rails. The pivot axles with guide rails of the foot and seat members are positioned near each other on each side of the connecting joint. The foot member has an additional axle with guide rail in order to keep the end of the foot member within the level of the frame. When the back member is lifted, the foot member will be lifted at the end near the seat member due to an inclination of the guide rail. The seat member will follow this movement. However, the inclination of the seat member will be dependent of the action of the intermediate member, which in reality will control the position of this main part of the furniture. This will make the seat position flexible and dependent of the influence of the user and the direction of movement of the back member. In addition the knee area of the furniture will be lifted, which as mentioned above, is not always desirable.